The following structures have been solved or datasets collected: apo-Guanylate Kinase: Hg MAD data at 2.0 A, four wavelengths. Structure has been solved by MAD phasing and the refinement at 1.8 A is in progress. ERA GTPase: SeMet MAD data at 3.2 A, four wavelengths. We were not able to solve for the 16 Se sites due to the low resolution and low signal/noise ratio. ERA GTPase: native data at 2.6 A. apo-Guanylate Kinase: native data at 1.8 A. ERA GTPase: Hg MAD data at 2.6 A, four wavelengths. MAD phases have a FOM of 0.60 before solvent flattening. Tracing is in progress.